CVE-2023-4809
Freebsd ≤ 12.4
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-4809 is a high-severity Improper Handling of Additional Special Element (CWE-167) vulnerability in Freebsd Freebsd. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique OS Credential Dumping (T1003); ranked in the top 44% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-54653
Vulnerability Data
In pf packet processing with a 'scrub fragment reassemble' rule, a packet containing multiple IPv6 fragment headers would be reassembled, and then immediately processed. That is, a packet with multiple fragment extension headers would not be recognized as the correct…
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ultimate payload. Instead a packet with multiple IPv6 fragment headers would unexpectedly be interpreted as a fragmented packet, rather than as whatever the real payload is. As a result, IPv6 fragments may bypass pf firewall rules written on the assumption all fragments have been reassembled and, as a result, be forwarded or processed by the host.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require correct input parsing and special-element handling during development.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure development lifecycle mandates input validation and handling of unexpected data elements.
A.8.26 explicitly lists resilience against SQL injections, input validation, and output controls as application security requirements to identify/address (items d, j, l, m, p), which stops exploitation of mishandled special elements in many but not all cases (e.g. non-input vectors or incomplete implementation remain).
A.8.27 mandates security-by-design principles including distrust-external-input, data validation/sanitization, least privilege, defense-in-depth and secure design reviews that catch many (but not all) additional-special-element cases before they ship; a bounded remainder of implementation-specific or second-order cases can still reach production and be exploitable.
Secure coding standards directly require correct handling of all input elements, eliminating this weakness.